Fidget Spinners

You see them everywhere, but why use someone else’s? Have your students make their own and learn about balance, symmetry, friction, the principle of the conservation of energy, good design and more. This is a great project to have students to do some testing and iteration.

Some basic rules of making a fidget spinner:

A fidget spinner needs a spinning mechanism (generally a bearing) in the dead center of the spinner. The standard bearing for fidget spinners has an inner ring and an outer ring. You hold the inner ring while the bearings allow the outer ring to spin around the inner ring.

There are two sizes of bearings 608’s which are 22mm in diameter (which are the most commonly used bearings) and r188 which are 12.7 mm in diameter. The r188 according to this article and others are said to be faster and more efficient. They all cost from a dollar or less for the basic to 20 or 30 for the super deluxe versions.

You can 3D your own bearings, but they are not as good (but free). Here is one example. The STL included in this post by Josh has its own bearing unit included in the file.

I made some holders for the inner ring to make it easier to spin in one of the STLs attached. Again this will depend on the bearings you purchase. You want to make it easy to hold the inner ring without touching the outer ring.

Spinners work best with counterweights that are spread out evenly. You see lots of three arm designs. Two arms are the easiest to make. I found four weight designs are also not too bad.

You can buy lots of different counterweights from LED light versions to ball bearing versions. A cheap version that is easy to use is steel nuts (as in nuts and bolts). The nuts are also easy to set into your design (hexagon).

You do not need that much weight and some design work okay without them. Trial and error is your only true source of wisdom.

Hand size is important in the design. Be sure students make a paper prototype to scale so they can test the fit of the spinner in their hands.

Some easy ways to get started:

Have a template for the students and have them add or subtract their creativity from it. You can start with either a circle of six or seven cms with a 22mm hole cut in the middle (or instruct them to do so) or start out with a rectangle of a few cms wide and six or seven cms long (again, 22mm hole in the middle). Instruct your students to balance the weigh as much as possible.

Beatifying your design can take a number of avenues. You could add stuff on top or cut into the template. Shapes, text, small STLs of logos or icons found from the internet all work well. I had some kids line draw a circular art piece on paper, scan it in, convert to SVG and extrude in Fusion360 or TinkerCAD. Lastly, they cut 22mm hole in the middle using the software.

You can also start with a square, pentagon, etc. as your template or make a good single arm. Then, duplicate and arrange it symmetrically.

Iteration

The more complicated the design gets, the more it might need adjustment and tweaking (and multiple prints to test this out). This can be a great project to set some design criteria (general ideas/testable goals about the look and/or operation of the spinner) and create/test/tweak/repeat until it meets those criteria as much as possible.

The sample STLs and photos attached were all designed by either myself or my students. You can find a billion more online, but of course, it is better to make your own!